Telegraphy.



` L. M. vPOTTS.

TELEGRAPHY.

APPLIUATION rxLED JULY 1,1908.

Patented lApr. 4, 1911'.4

4 SHEETS-SHEET 1.

.5 SMM@ .I

L. M POTTS.

` -TELBGRAPHY. APPLICATION FILED JULY 1,1908.

988,81 1 Patented Apr. 4, 1911.

4 SHEETS-BHEBT 2,

L. M. POTTS.

TELEGRAPHY. APPLIUATION FILED JULY 1, 190e.

IVf

Patentd Apr. 4, 1911.

i L. M. POTTS.

TBLBGRAPHY. APPLICATION FILED JULY l; 1908.

lPatented Apr. 4, 1911.

4 SHEETS-SHEET 4.

l UNITED siarns PATENT OFFICE.

- LOUIS M. POTTS, F BALTIMORE, MARYLAND, ASSIGNOR, BY MESNE ASSIGNMENTS, T AUSTIN McLANAI-IAN, 0F BALTIMORE, 4 MARYLAND.

TELEGRAPHY.

Specification of Letters Patent.

Patented Apr'. 4, 1911.

implication ined Juiy' 1, 190s. .seriai no. 441,357.

lo all whom 'it may concern:

le it known that I, vLOUIS M. PoTTs, a citizen of the United States, residing at Baltimore, in .the Stateof Maryland, have. invented certain new and yuseful Improvements in Telegraphy, of which thefollowing is a speciication.

The primary object of this invent-ion is to iniprove the operation of'tliat class of telegraph linesy wherein the home receiving instrument is in vthe normal operation of the line non-responsive to current sent out from its lown station, but responsive to ciirient receivedfrom a distant station. The rendering of the heine receiving instruments operiwhich 'is composed of electrical resistance and capacity,l the value of which mustl be regulated so as to correspond to those of.

the real line.` This Aprocess may take conf siderabletinie, particularly when the condition of the wire -is changeable or unstable; or when other conditions are such as tol demand a very accurate balance. In systems ,where the artificial line is composed ot a considerable number of sections, with dist1'ibuted. capacity, it is,neces'sary to separately'- adjust each section, so that the ylength of time consumed may be considerable. In any' case, by present methods,'it is necessary to stop the transmission in both directions and cut olf the signaling current 1 at one terminus while the other balances. Then the first terminus .has balanced, the

process is then reversed; and not until both ends have balancedrean the line be yagain 40 operated; and, during this interval, the wire has been completely-out of use. The present invention proposes aniethod and means by which this'condition is obviated, and makes it possible to operate the .wire at a traction F15-of its full capacity continuously' without.' an

artificial linefbalance. While the line is operating` atthis 'capacity, both ends can be rsimultaneously balancing. When both y. ends are balanced the throwing ota switch at each station makes possible the full Idii- -plex operation of the line.

A furthe-i' object'pot this invention is to provide for the maintenance ot' synehironisin under the above conditions.

Other objects of the said invention will hereinafterinoi'e fully appear.

Although applicable ,to any system` in which a definite time relation can be established betweeii'the signals passing in opposite directions on the saine Wire, the present invention'ha:=; been developed withspccial reterence to the Rowland telegraphic systeni, a forni ot which is shown and de- `scribed in U. S. Patent No. 713,497 to Henry A. -Rowland granted Nov.l 1l, 1902.

ln the Rowland system an alternating current is sent over the line continuously and this current is employed both for trans-v mitting signals aiid synchronizing; the signals consisting in reversing certain combinations ot the waves of said alternating cur= rent. 'Ihe miiltiplex feature of the system is accomplished by synchronous operation of current distribiiters located at the terminal stations.

In the case of the Rowland octoplex each of the four operators'at eachend of 'the lineis given the use of.. the line wire for one! fourth of the time at regular recurring intervals, and in addition the line is duplexed by the polar duplex method which allows two transmissions to take place simultaneously, so that four transmissions in each direction or eight in' all may take place over the saine wire. Hitherto it has been necessary tostop, all transmissions over. such a line' when balancing'the artificial line for duplexing. The present invention contemplates, in such a ease', that durinor the bal ancing ot' the line at least two of the operators at each end of the lineshal-l have use of the line without interfering with each other oi' with the balancing. Y

In order-to more fully describe my said inveiition, reference-will be had to the accom.- panving drawings, wherein,

Figure 1,`is a diagram. of a duplex teley graph linel embodying my said invention;

lFig. 2, a diagram to illustrate thegroiiping omiaea, and' rige, indient-e ai' diag-mm. ai@

vrelative positions at the two ends of theline 'of the several brushes of 'said commutators omitted from F ig. 5.

. having'two windings, one forgthe'-reallinev In Fig. 1,' A and vvB indicate two stations at opposite' endsof ,a duplex telegraph line; '1 the receiving main line' relays, whichjrnay be of the. usual tormofpolarduplex relay '2, and the vother .for the artificial line 3, connec-ted in the usual mannerv through resistance 4 and capacity 5 to earth; '6 the `main line transmitters, the tongues -ofwhicln are.

mitted to. line through said contact. wWhen la signal is sent, which occurs throught-he operation of a keyof a keyboard, this causes thetongue of the transmitter to pass over to the other .contact'sending an'alternating current wave to line of different polarity from.- the'normal. The reversal of these waves inf certain combinations forni the signals. The

-time intervals of the severall transmissions are provided `tor by using in connection with the keyboard, a current distributer or sunflower which allows the respective operators the use of a given transmitter yat denite intervals, allot which is fully described in said patent to Henry A. Rowland,

Thepresent invention is not directed to any particular'form of line transmitter and means for operating the same@ This saine holds true with respectto thereceiving apparatus. The relays 1 which I have shown may be the regular line relays of the Rowllandsystem and record the message by actuatin printers, such for example, as describe in said Rowland patent; but I-do not wish to limit my invention except vwherein specifically pointed out Ito said, system or any part thereof.

In order to continue-'theoperation of the line while the artificial lines are being adjusted, l have provided means whereby the receiving linerelay at one station may be made to receive signals only at such times as current from its station is not being sent out, which permits the artificial linefat a give-11 station. to be adjusted while current is being sent out from that station without interfering with the reception of signals from the other station. The means which l have shown foi accomplishing'. this, comprise a rotary{circuit-changing ldevice connected atv 'esseri cach station. in circuit u-'ith'theinam line between the transmitter and the receiving line relay through a two-pole double-throw switch 7. These rotary circuit changing devices comprise .each conducting ringsl 8 and 9, the

`former beingof continuous metal while the latter.. isdivided by insulation 10l into two halt' sections or segments 11'and 12. These 13 and 1 4' which are inpermanent electrical connection with each ot-her, as through conductor 15,- and vare driven preferably in synchronism in Iany suitable way, the brushes 13 and 14e-atv one 'end ofthe'line being staggeredlSOO from those at the otherv the switch 7 permanently connected to the receiving relay side ofthe main line as shown. Each ring-.8 is'permanently connected to .contact 18 of its respective switch,

19, 19, are instruments, hereinafter more fully described, for'indicating the correct adjustment ofthe artificial lines,

' With theswi'tches 7 thrownas shown in thefull line position in Figl, the line will operate at hal'fcapacity, during which time the artificial lines at both-stations may be balanced simultaneously.

YWhen the switches 7, Fig.

passing over 'segment 11 the tongue of the transmitter 6 at that station is in electrical connection 'through switch contact 17,"seg' ment 11, brush let, conductor 15,' brush 13,

`ring 8 and switch contact 18 .with the split of the main line relay at that station, and while brush 1st' is thus passing overtransmitting segment 11 at station A, brush 1l at station B is passing-,over segment 12 which is grounded through switch contact '16 at that station. Connection at this time will be complete from the split ot the receiving relay at station B, through' switch 'Contact 1S, ring S, brush 13, conductor 15,' brush 14, segment 12, switch cont-act 16 to earth. Therefore, while brush 14 at station A ispassing over segment 11, signals may be sent l out from the transmitter at station A aiid received'on 'the receiving relay at station l-l,

V1, are thrown vto the full line positions shown, it will be seen that while brush 14 at station A isyrings areprovided respectively with brushes and during this time the receiving relay at 'station A may respond to these signals, but

the transmitter at station B cannot during this time send signals to stat-ion -t'er the reason that the brush 1l at station B is, during such interval, out of engagement with the transmitter segment 11. The conthe trailer`14f at that station is passing over segment 12, an

ditions are exactly reversed at the two stations when the brushes 18, 14 occupy the halves of the rings opposite those upon which they are shown iii the drawings. Therefore, the artificial lines at both stations may be adjusted simultaneously luntil a affecting the reception of signals at the other end. With the apparatus shown, the line will then be operated at one half its full capacity during the balancing.

- In Fi 2, is indicateddiagrammatically blocks o signaling'current impulses, wherein Waves shown 1n full linesindicate those sent out from station A duringfthe time the waves in dotted lines those received from station B while the said ytrailer 14 is passing over segment 11 at.

station A. The diagram Fig. 2, shows the current as'it would appear at one end of the i line; at the other end there would be a relative displacement between the two currents sent out from opposite ends due to the retarding eect of the Iline capacity. In the Rowland loctoplex each ot' these blocks et signalimpulses represent two transmissions, tol each of which is-devoted fourteen inipulses. `This particular division of the waves is convenient in the Rowland system, but: the present invention is not limited to any'particular classification or grouping of signals.

i lVhen the-proper balance is obtained the switch 7 maybe thrown to the-dotted line positionl shown in Fig. 1, when the line may be worked at'its vfull capacity.- In this latter position of the switch 7, the line from instrument. l have shown in Fig. 1 for accomplishing this,

the transmitter is connected direct to `the lsplit of the receiving relay through the switch contact 17, thus short circuiting the.

rings-8 and 9.

l The adjustment of the artificial lines to obtain a correct balance, may be indicated in any of many different ways, and I do not limit my invention to any of' these except where specifically pointed out in the claims. The method of indicatiiig a balance illustrated in Fig. 1, consists in connecting two instruments of the electro-dynamometer'type in circuit in such a manner that the currents in the two movable coils shall differ vin phase from 'each other, and connecting the fixed coils in such a way that they shall be excited by a strong current similar in charactei to the signaling current, and balancing the line until there is no deflection of either l The instruments 19, which I comprise each twoinstruments of the electro-dynamometer type wherein the fixed coils 20 and 21 are connected in series with the main line between the transmitter tongue and the split of the main line receiving relay, while the moving coils 22 and 23 are connected in branch circuits from the beginiiing of the real line to theV beginning of the artificial line, the coil 22 in sei'ies with either capacity or self induction 24 and the coil 23 in series with' a. resistance 25, the current in one movable coil being dephased with Arespect to the other movable coil 23 of the same combined instrument 19. WVhen there is no'deflection of either movable coil oi the two instruments making up the com-l bined instruments 19, there will be a balance between the real and the artificial` lines. v

It will be readily seen. that when the switches 7 are thrownlto that osition shown in the full linesin Fig. 1, wien the line .is worked at half capacity, the balancing instruments at the respectivestations will not be a-tl'ected'by incon'iingcurrents but only by currents generated at the home station, so that the adjustment of the artificial line may be carried on until the needles of the instruments 19 indicate zero, when a balance will lhave been obtained. This operation at each station being independent of the received current at that station may be carried on at both'ends of the line simultaneously while two 'transmissions are'taking place in each direction.

In Fig. 3, I have shown another arrangement forindicating a balance of the lines, which may replace that shown in Fig. 1. The ordinary way of indicating a balance of a duplex telegraph line is by feeling the tongue of the main line receiving relay and noting thereby the effect of the out going current thereon. The method illustrated in Fig. 3, is based upon this general idea. In this case, I employ in addition tothe main line receiving relay 1, an indicating relay 26 `which may be an exact duplicate of relay l; replace the circuit-changing devices 8 and 9 (Fig. 1) by a comniutator having six rings 27, 28,2930, 31' and 32, and replace switch- 7 (Fig. 1) by a three-pole double-throw switch 33. The commutator rings 27, 28, and 32 are divided into two insulated segments while the rings 29 and 31 are metal all around as indicated, the said rings being shown developed. The commutator brushes 3-1- are electrically connected inI pairs and may be driven 4at the desired speed in any desired way.

'lVith the parts connected as shown and the switches BS'thrown to the position indicated in full lines in the drawing, the relay '1 is connected in circuit when current is being received from the distant end, and the relay 26 is connected in circuit when current is being sent out4 from the home station, since thc'said relays are connected in circuit with opposite segments of the' split rings 27, 28 30 and 32. It is evident, th lrefore, that therelayll will be affected onlji` by thelincoming current and relav 2G by out going esseri current only. Now if the line is properly balanced, the outgoing currentwill have no effect upon relay 26, therefore, by simply feeling the tongue of relay 2li-itc determine when the outgoing current has no effect upon it, an indication. of the balance is obtained.

lVlien the switch 33 is thrown to the other position` or the full capacity position, the segments of the rings 30 and connected to the relayI 26 will 4be short circuited, thereby cutting therelay'Q out of circuit- The re lay 1 will .then be in ircuit continuously .until itis found necess ry to throw switch 33. This method of line operation whereby the line may be continued in use during the balancing though operating at reduced capacity -is shownin Fig. 4 'asl applied to thev Rowland octoplex synchronous system.l In this diagram, v35 and 36 indicate respectively the positive and negative local supply mains of a 110 volt D. C. circuit, 37 a split crown commutator, the brush 38 of which connects through a brush 39 on a collector ring 34 to the positive local main 35 ;`41 a transformer,

the outer-terminals of the primary of which connect to opposite sections 'of the commutator 37 while an intermediate terminal of lsaid primary is connected to a switch`.blade 42, which,;it thrown to contact 43 connects all the terminals of the primary of the transformer to the same side of the line'35, 36, thus cutting the transformer out of operation. When the switch blade 442 is. thrown to contact 44, normally in electrical circuit with .-a switch blade 45, the trai'istormerI will be operative continuously if the switch blade 45 is on contact 46, which is connected direct to the negative supply main 36,0r the transformer will be operated at regularly] occurring intervals or halt-the time vif the 'switch blade 45 is thrown to contact 47 while thev blade 42 is on contact 44, the said contact 47 being connected to an insulated half or segment of the split ring-48 having a contact brush- 50 permanently electrically connected through a Contacty brush 51 on ring 52 to the negative supply main 36. 'This transformer supplies the alternating current tothe main line, and for this purpose the outer terminals et the secondary coil are connected to opposite contacts 53 and 54. et the main line transmitter 6, while a-n intermediate terminal of said secondary is connected to earth as shown. Normally, that is as longas no signals arebeing sent by trans 4mitter 6, its tongue is biased so -astorest normally against Contact The operation of the transmitters inllig.. 4 is the'saine as described with'relatioii*toz Fig.l1. ln F ig. 4, however, I have indicated'- diagraiiiinatically the keyboard and tlie transmitting coininutator connections of the Rowlandl octoplex for operating the transinitter. s shown the transmitter has its split connected to the positive side of the cas eration in said patent in lthe ollr'iwingl supply line; oney of the coil terminals nectcd through a high resistance to the negative side oit said circuit, and vits other coil terminal connected. through resista-nce' 56 to the brush ,57 of a sending cominutator.

58, which is divided into four eqnalgroups of insulated segments, each otwhicls connects to a separate keyboard iiidicateddyfl the tour keys 59, 60, 61' and 62, all of 'Wl ich connect to the negative side of the local vcuit 35, 36. The commutator 58 is shown in Fig. 4 in development. 4ln practica', eacle key of a keyboard is provided with treo cone tacts which connect to two segments in its respective group on the sending commutator. Means are also provided whereby the-keys of the keyboard may be 'operated at certain times so as not to interfere with cach other; but these are details whicliforin no part of the present invention, and for adescription orn which the reader is referr to the Rowland patent before referred to.'

'63 represen ts in development the receiving coniinutator, which like the sending commun tutor, is divided into four equal groups of to points about voluins :trein terminals of the 600'oh1ns resistance The brush M72 is driven in synchronism 'vi-ithxiie vibrationfof the tongue T3 ot the line' relay 1 so that. the main line current is reproduced locally through the relays 64, 67, each alternate relay in a given bank receiving current in. the same direction, but adjacent relays in' opposite directions. Througlrthe reversal .of the line current impulses as above described, the tongue of the urelay 1, by re-4 maining againsttlie opposite contacttr'oni the. normal for the time of suoli reversal, causes a reversed impulse tobe sent to the selecting relay connected to the segment of the receiving commutator at that instant under the brush of said coniniutator, thereby causing the movement of the tongue .of the selecting relay outof its normal posi: tion, which may be made to. record the sigi-k example, by the operation ort-.a printer as shown and described insaid Rowland patenti The operation y.of 4 the receiving `and transmitting commutators in 'the present however, di'ers from their mode of op respect: In said patent-there 'is synchronous iii;

' nal thus received in any desired way, as-for,

operation between the transmitting commutator at one end of the lineand the receiving '-colnniutator at the distant end, but as between the sending and'receiving commutaftors at the same station thereis'absolutely independent operation. Moreover. in the patent referred to, the` generators of the alterating current at the opposite ends of the line operate independent of each other.

In thecase of the present invention, the

brushes ofboth sending andreceiving commutators, as well as the brushes 38, 39, 50,

'51, 14 and 13 are alll driven byv a' common (the same) motor 7ll'of which 75 represents the shunt field. The motors 74 at each end of the line are driven in synchronism with the line alternating current and therefore with eachother, which synchronism may be maintained'in the following way: On the shaft driven by the motor 74 is a `trailer carrying a brush 7 G which travels in contact with a crown commutator 77, shown in development yin Fig. 4. The seglnents of this crown commutator are of such a number and the brushes driven at such a speed that the' In series with 'the armature of the motor 74,

is a resistance 81, and on one side of this resistance is connected the synchronizing tongue 80, while the other side of said resistance is connected to brush 76'through a collector ringf82jand brush 83 thereon,the

latter being mounted Ion the same trailer with 'and permanently electrically connected to brush 76.' The connection between? the commutator 77 and the double-pole switchv 84 will for the present be disregarded.

The tongue 8O of the main line relay-1 is kept in continuous vibration by the alternatingcurrent from the distant station, and the trailer or brush 76 is kept in continuous rotation by the motor. If the tongue 80 of the relay is on the side contact which is con-l nected tb the set of segments of the crown commutator which'the trailer is touching at thesame time, (contact 78' Fig. 4) it will be seen that the resistance 81 is short circuited; while if the tongue 80 of the main line relay is on the side contact of the relay which is not connected to the set of- 's'egments of the crown coinrnutator which the brush is touching at the saine time, the resistance will be in series with the armature of. the motor.

In one case the -v-.armature will receive a muchy greater current than in the other.

Consider, first, the ycase when the vibrations of the tongue of the main line relay and the rotation of the brush arm bear such a relation to one another that as long as the tongue is against. a givenk contact the brush 7G is in contact with the segments connected to that contact. If this condition is maintained it will be seen that the resistance 81 is continuously shunted.

Secondly, consider the case when the vibrations of the tongue of the main line relay bear such a relation to the rotation of the lbrush arm that when the tongue is on the cont-act 78 the brush is on the segments connected to contact 79, and when the tongue is on the contact' 7 9 the brush is on the segments connected to contact 78. If this condition is continuously maintained it will be seen that' the resistanceSl is con tinuously in circuit with the armature.

Thirdly, consider any case in` which the vibrations of the relay'tongue and the rotation of the brush arm have some relation between the above two. If any relation be; tween the firsttwo mentioned is continuously maintained, -it will lbe readily seen that at rapidly recurring .intervals the resistance will be in circuit and out of circuit. Depending upon the relation between the vibration of the tongue andthe-rotation of the brush arm, the intervals during which the resistance 81 is in circuit and out of circuit vwill vary in length, and in addition to'the regular current, flowing through the armature, there will be a pulsating current flowing through the same and the strength of theseiinpulses will depend upon lthe relation existing between the vibrations of the tongue and the rotation of the brush arm. Consequently, while the relay tongue is vibrating in unison with the rotation of the lbrush arm, there can bevarious amounts of current fiowing through the armature of the motor` depending upon the relation of the relay tongue and the rotation ofthe brush arm. This is in brief the theory and operation of the Potts s vnchronizer employed in the Rowland system.

IVhen operating the line at half capacity, as herein described, during the adjustment Vof the artificial line, it will be seen ythat the drawings by the two halves of the commutator` lying respectively on opposite sidesof the insulator 85, and connect 'opposite crown sections of the halt helovv said insula- .n tothe blades ot a trio-pole douhlethroiv itchfsel', 'While the other segments' above 'l insulatioh are connected to the relay ntacts. mi

i wo of the. contactsof switch 84 snbfiect to the synchronizing action of thel mein line .relay tongue continuously. When the svt-itch Seis thrown tc fhe other contacts shown, this ciits ott' connection from the loiver halt of the coniniutator'', and the lin-c relay contacts, so that the motor 74 Will receive synchronizingact-ion from the line relay'only Whi the brush itl is passing over that half of the co'iniuiitator T7 above the insulation S luring the other intervals, thatisfwhen the main line relayis not receiving currentironi a distant station, the armatureoi? motor Ej'l receives current through compensating resistance S6 approxi mately equal to that received by Way of the main line relay tongue. thereby preventing a tendency to oscillations synchronism which would otlnertvise be present.

ln Fig. 4, the apparatus atoneend oit the Aline only is indicated. This is 'of bourse cupliT cated at the ,other end except) as to the relative positions .of the -commutfator brushes which are `as indicated in Fig.' 6. Calling one end of the line station A 'and the other station B, it will be seen that' correspond-- ing brush-es at the two stations have a ,relative displacement of 180. Assumingl that each end oiF the line is equipped with the apparatus and connections shown in Fig. 4,

the method of. starting-up the machines at tiro-two stations is 'as follovsz-The motor Tet at one :of the stations is started andrun up to the proper speed. v The switches 7 and Sel are. set' 'to-the full 'onposition shown in Fig. lli, andthe switch, larms 42 and 45 also occupy full on positions in which they areV shown. This station then sets the speed. At the other station, the one synchronizing, the line switch 7, and the synchronizing switch 84e are set to the full on position and the switch arm e2 shifted to 'Contact 43 con-ipletely cutting o the source of signaling A The. motor T4 at current Vat that station. the stat-ion synchronizing being started, the letter l is then -found. The process of "t i'inding'thezletter is fully described in said Rowlandpatent hereinbefore referred toand need `no here-be. described in detail. Briely it consists in causing the receiving sunower -brushat one station, the station synchron'iaivelj.7 to the relay contacts 78 may have use of the line. i

the. switch Tis thrown to the halt time posi,y

esagera ing, to automatically soadjust its angular brushes will arrive upon corresponding. segments simultaneously. The line switch 7 at the synchronizing end is-then turned to the halttime position;1 vthe signaling current switch blade et); shifted vback to contact 44,

` connecting the" source of signaling current at that end of the line, after which the syn-v chronizing sWi-tchet at that .end is turnedtothe half-time "position, As soon as the operator. at theend setting the'speed perceives by the vibration .oi-' the inain line re lay tongue that the distant stationswitches .are set-for half-time operation, he in turn throws his switches 7 and 84 to thel halftime positions, when thema-chilies are ready for operation at 'half capacity. `The artiticial lines'at; the two ends are then adjusted to tobtain a balance," during which tune the' line nia-y' be operated ata fraction of its full cap: city described. The operatorsat the two stations notifyeach other when' a balance is obtained, and when this facthas been exchanged, line and synchronizing switches T and Set at both sta-tions are` thrown' to full on positions. lf it is desired to test the balance at, any, time when the machines areoperating 'at full capac1ty, the request forA half-timeoperation is sent to the" distant terminal' and the switches are thrown to the half-time positions, the end synchronizing throwing its switches first so as not to dis-v turb the synchronisni.

' lt will bel seenby a referencefto Fig. tl,

that ivlien the line switch 7 is thrown to the full capacity position in Whic le is shown in lsaid figure, the' operators at all four keyboards -59, 60, 6l and' 62 as Well-as all or" the receivers operated by relays 64. 65, 66 and 67 lVhen, however,

tion, operators at keyboards 61 and 62 alone ata given station may' usethe line, and receivers operated hy banks of relays (ist and (l5 alone'niay receive. At the other` station, during the half` time operation, keyboards corresponding to keyboards 61 and 62 and receivers operated by relays corresponding'. vto banks 66 and 67 are operative.

`What l claimis Vll() 1. The method of operating a duplex teley graph line `which consis s in operating the line duplex at a fraction ofits full capacity `without the use of `the artificial line. and adjustin?,q the artificial line duringsuch time.A

The niethod ot operating a duplex telo graph line which consists operating the line duplex ata tract-ion ofits full capacity Without the' use of the artiticialline," adjustingthe artificial line during such time, and

Uthen operating` at full capacity aftpy'the bulance is obtained. Y The method of operating a duplex telegraph line which consists in operating the` line in multiplex capacity at a fractioififoits full capacity Without the use ot thearti-y icial line,'adjnsting the artificial line during.- such time, and then operating the line at full capacity with the use of the artificial line lafter the balance is obtained.

4. The method of operating a. duplex tele-y graph line which consists in operating the line inmultiplexfcapacity at one-halt' its full capacity without the use of the artificial line, adjusting theartiieial line during such time, and then operating the line at full capacity with the use, of the artificial line after the balance is obtained.

The method oi. operating a duplex telegraph line which consists in operating the line duplex at a fraction of its full capacity, and during this time simultaneously adjustiing the artificial lines at both ends to obtain a balance.

'6. The method of operatingl atelegraph line supplied with a periodically varying signaling current which consists in dividing the impulses of this currenty into groups which are transmitted to the line intermittently and establishing between the groups thussent out from one station and those sent out from a distant station a definite time interval, and from each station during a portion of the time only that the line is operative.v

7. yThe method of operating a telegraph line supplied with a periodically varying signaling current which consists in dividing the impulses of this current into groups which are transmitted to the line intermittently and establishing between the groups thus sent out from one station and those sent out from a distant station a definite time interval so that the transmissions shall take place alternately, and from each station during a portion of' the time only that the line is operative.

8. The method of operating synchronous .telegraphs which consists in utilizing the same current for signaling and synchronizing and sending said current in the two directions over the line intermittently and atdifierent times.

9. The combination .with a telegraph line, of circuit connections 'for sending out signals from a given station a fraction of the time and receiving signals during a fraction of the time, said sending and receiving occurring intermittently and at different times, circuit connections for sending and lreceiving signals at saidstation all the time duringy the operation of the line, and means operative at will for rendering the line operativein either of said capacities.

10. The combination with a 'duplex telegraph line, of a main line transmitter and receiving relay at each end of `said line, and

`automatic means'to intermittently connect and disconnect the said transmitter and relay to and from each other at each station. g 11. The combination with va telegraph line and a source of signaling current connected thereto at each ot' two stations. of automatic means at said stations to permit said current to be sent out to line from said stations intermittently and at alternate times from the two stations, and switching means operative at will to cause current to be sent to line continuously from both stations.

12. The combination with a duplex telegraph line-of a 'switch opera-tive at will for changing the line from full capacity to a fraction of its full capacity, and an automatic circuit-changing device connected to said switch and adapted to time the trans- -mission of signals over the line when said switch is thrown to the position in which the line is operated at a fraction of its full capacity so that signals in opposite directions may be sent intermittently and at ditl'erent times only.

13. The combination with a duplex telegraph line, having a receiving relay and .a transmitter connected therein, .a circuitchanging device and a switch connected between said transmitter and receiving relay, said circuit-changing device in one position ot' said switch acting to connect the transmitter to thc line through the receiving relay during halt' the time and to disconnect the t'ansmitter 'from line during the remaining half of thetime. the receiving relay during the latter halt' being connected to receive signals from a `distant station.

1i. The combination with a duplex telegraph line, of a balancing instrument to indicate the. correct adjustment ot the artificial liiiefand circuit connections and automatic means to render said instrument operative at such times only as current is not being received from th'e distant station.

15. The combination with -a duplex telegraph line, of a balancing instrument t0- indicate the correct adjustment ot' the articial line. and intermittently acting means to render said instrument operative when current is being sent out from the balancingl station and to render said instrument inoperative when current is being received from a distant station.

1G. The combinatin with a duplex tele- `graph line, of means for indicating a correct adjustment of the artificial line at a given station, comprising an instrument` responsive to currentv from a distant station only and an instrument responsive to current sent out from the home station only.

17. The combination with a duplex telegraph line, of means for indicating a'l correct adjustment of the artificial line at a given station, a 'main line signal receiving relay, a'second relay, and switching apparatus to render the said first relay operative only 1:;.1 eeeeii by current from a distant station andA thel second.. relay operative only by current` from the home station. i

18. The combination with a telegraph line, of synchronizing apparat-us at'two stations in ysaid, line regulated primarilyl by the effect of the main line current, the synchronizing apparatus at lone station beingrespo'nsive only '-to currentsent out from the distant.

station, and means for sending out said current intermittently and atsuch times only as current isnct being received from the distant station.`

19. The combination with a telegraph line, of a source' of current connected thereto, synchronous apparatus regulated primarily by thel eect of the current fromsaid source, 'andnieans to render said synchronous deyice responsive to the synchroniZing action of said-current. dnringihalf of the time .ot theoperatio'not' the lineend intermittently.

20.v` Theeomhinetion *with e telegraph line, ot a Vmain I line transmitter and relay, local'transmitting means comprising a circuichanging device for operating the transmi ter, local receiving means comprising` `a circuitechanging device coperating with the main line relay, a circuit-changing device whereby current may he sent to line through said transmitter only a part of the time and intermittently, asynchronous motor driving` said 'circuit-changers, and synchronized pril ierily `ley the eii'ect of the line current, and a circuit-changing device and connections whereby said motor is syn. chronizedhy seid current at such times only asl current is being received et its station from a dist-ant station, said times'occurringv intermittently.

2l. The combination witha telegraph line, of a source of current connected there` to, synchronous apparatus regulated primeA rily by current fronisaid source, and means to render said synchronous device responsive to the synchronizing action of part of said current during a portion of the time ofthe operation of the line and intermittently, and

local compensating means operative during' the rest ofthe time tomaintain the synchronisin. f

QQ. The combination with e telegraphv of ineansf'to operate said line in duplex ca line operative- ;tor signals in .opposite direc tions intermittently and tit-different times,

eacity, ineens to automatically render the 

